753 Smokes on startup

[nashfireman]

Just bought a 1995 753 with about 4000 hrs. The machine starts very easy. Bump the key and its running. On a cold start( using the glow plugs) it blows blueish black smoke( and I mean alot of it ) for about 30 seconds. I can hear it missing until the smoke clears. I have checked the glow plugs and they are ok. I have had the injectors rebuilt and it seems better but the smoke is still there. Before rebuilding the injectors the smoke would last longer than 60 seconds. After she stops smoking she runs great ! Plenty of power and no smoke under a load. I had a 743 for several yrs that would smoke a little on startup but never this bad. Is this normal for a 753? If not, what else do I need to check? Thanks for all your help.

 

[nashfireman]

I forgot to say that the fuel filter and air filter is new. Good fresh fuel in tank. Also, is there a easy way to get to the fuel sender? I tilted the cab and I cant even see it !

 

[Fishfiles]

I forgot to say that the fuel filter and air filter is new. Good fresh fuel in tank. Also, is there a easy way to get to the fuel sender? I tilted the cab and I cant even see it !

valve guide seals could be a cause , when the engine is stopped oil will drip pass the seals and on crank up it will smoke till the oil burns off -another cause could be compression

 

[frogfarmer]

That machine should not have any notable smoke. It may puff at start up but that would be about it. With a miss you are defenitely sending out raw fuel and a fair amount of smoke. Low compression could be a cause but it would likely be hard to start at times. I would check the valve clearance at the rocker arms. Valves that are too tight can also cause the problem. And as a long shot the governor in the injection pump could be sticking or have a broken spring causing an over-fuel condition that fouls a cylinder on startup. I would start with the valves.

 

[nashfireman]

That machine should not have any notable smoke. It may puff at start up but that would be about it. With a miss you are defenitely sending out raw fuel and a fair amount of smoke. Low compression could be a cause but it would likely be hard to start at times. I would check the valve clearance at the rocker arms. Valves that are too tight can also cause the problem. And as a long shot the governor in the injection pump could be sticking or have a broken spring causing an over-fuel condition that fouls a cylinder on startup. I would start with the valves.

Thanks for the advice. I think I will check compression first and then if thats ok I will move to the valves.

 

[frogfarmer]

Thanks for the advice. I think I will check compression first and then if thats ok I will move to the valves.

If the valves are tight it will show low compression or at least it should. All depends on how far the tolerances are out.

 

[Rookie]

Blue smoke is burning lube oil, black smoke is unburned fuel from over fueling, usually due to lugging, clogged air cleaner, or improper rack setting. Blue smoke on startup is fairly normal on high hour well maintained engines and usually goes away once thermal equilibrium is achieved. This is caused by normal wear.

 

[Rookie]

Blue smoke is burning lube oil, black smoke is unburned fuel from over fueling, usually due to lugging, clogged air cleaner, or improper rack setting. Blue smoke on startup is fairly normal on high hour well maintained engines and usually goes away once thermal equilibrium is achieved. This is caused by normal wear.

Forgot to mention that you can perform a leak down test to confirm the condition of the valves or piston rings.

 

[jklingel]

Forgot to mention that you can perform a leak down test to confirm the condition of the valves or piston rings.

So what is white smoke? If I start up cold, I get a little bit of white smoke for about 1 second; just a good puff, then it is gone. That used to happen to an older diesel truck I had, too, every time I changed the fuel filter. There was no way (that I knew of) to re-fill the fuel canister manually, so I just filled it part way, stuck the filter in, and cranked the engine till she fired. Poof; white smoke. Is that just burning too lean? If so, I don't really understand why it smokes if there is excess air. Somebody clue me in. thanks. john

 

[Tazza]

So what is white smoke? If I start up cold, I get a little bit of white smoke for about 1 second; just a good puff, then it is gone. That used to happen to an older diesel truck I had, too, every time I changed the fuel filter. There was no way (that I knew of) to re-fill the fuel canister manually, so I just filled it part way, stuck the filter in, and cranked the engine till she fired. Poof; white smoke. Is that just burning too lean? If so, I don't really understand why it smokes if there is excess air. Somebody clue me in. thanks. john

A puff of white smoke at startup is totally normal, it just means it wasn't quite hot enough to burn the fuel for the first few revolutions. Ignore it.
White is un-burnt fuel, if you have bad glow plugs and crank the engine, it will puff white smoke till it starts.

 

[jklingel]

A puff of white smoke at startup is totally normal, it just means it wasn't quite hot enough to burn the fuel for the first few revolutions. Ignore it.
White is un-burnt fuel, if you have bad glow plugs and crank the engine, it will puff white smoke till it starts.

Taz: thanks. john